Specification: Type: Bluetooth Adapter Model: BTD 401 Weight: Approx. 20g Size: Approx. 2.2 * 1.5cm / 0.9 *0.6in For CSR8510A10 original chip: Yes Bluetooth standard: V4.0 + EDR dual mode Support Bluetooth CLASS 2: Yes USB interface: USB2.0 standard, downward compatible with 2.0/3.0 standard Operating frequency band: 2.4GHz 2.483GHz, using FHSS (frequency hopping spread spectrum) technology Operating range in open space: Approximately 20 50 meters Intuitive software interface, no complicated settings: Yes Applicable to operating systems: For Windows/ME/2000/XP/2003/VISTA/WIN7/8/8.1 For SP2/VISTA/WIN7/8/8.1, it is inevitable to drive, easy to carry! (For WIN8/8.1, it can be connected directly to the Bluetooth headphone speaker, other drivers need to be installed) Package list: 1 * Bluetooth Adapter (NO Drive CD) Note: 1. Please note that the package ONLY include a Bluetooth adapter. 2. Please allow slight error due to manual measurement. Thanks for your kind understanding.